Thermosettable polymer or prepolymer prepared from heterocyclic material having alkyl substituent, mono- or dianhydride, ethylenically unsaturated material and a hydroxide, carbonate or bicarbonate of a metal of groups I-A or II-A

ABSTRACT

Thermosettable prepolymers or polymers are prepared by reacting (A) the reaction product of (1) a heterocyclic material having one or more rings, at least one nitrogen atom and at least two substituent groups which have at least one reactive hydrogen atom attached to a carbon atom which is attached to a heterocyclic ring such as 2,3,5,6-tetramethylpyrazine; (2) a cycloaliphatic or aromatic carboxylic acid mono- or dianhydride such as pyromellitic dianhydride; and (3) a material containing a polymerizable ethylenically unsaturated group and at least one group selected from (a) a heterocyclic material having one or more rings; at least one nitrogen atom and at least one substituent group which has at least one reactive hydrogen atom attached to a carbon atom which is attached to a heterocyclic ring such as 2-methyl-5-vinyl pyridine or (b) a cycloaliphatic or aromatic carboxylic acid mono- or dianhydride group such as cis-5-norbornene-endo-2,3-dicarboxylic anhydride; with (B) an aqueous or alcoholic solution of a hydroxide, carbonate or bicarbonate of a metal of Groups I-A or II-A, such as sodium hydroxide. 
     These polymers or prepolymers when subjected to a thermoset condition by heat and pressure or by homopolymerization in the presence of or copolymerization with an N,N&#39;-bis-imide exhibit good char forming properties when subjected to a temperature of 700° C.

This is a divisional of application Ser. No. 754,696, filed July 15,1985.

BACKGROUND OF THE INVENTION

The present invention pertains to thermosettable polymers or prepolymersprepared from heterocyclic materials having alkyl substituents, mono- ordianhydrides, polymerizable ethylenically unsaturated materials and anaqueous or alcoholic solution of a hydroxide, carbonate or bicarbonateof a metal of Groups I-A or II-A. These polymers or prepolymers whencured provide products which have good char formation when subjected to700° C. in air.

Polymers or prepolymers disclosed in a copending application Ser. No.754,695, filed on July 15, 1985 prepared from (1) a heterocyclicmaterial having at least one ring and at least one nitrogen atom thereinand at least two reactive alkyl substituent groups (2) a cycloaliphaticor aromatic carboxylic acid mono- or dianhydride and (3) a materialcontaining a polymerizable ethylenically unsaturated group and at leastone group selected from (a) a heterocyclic material having one or morerings and at least one nitrogen atom and at least one substituent groupwhich has at least one reactive alkyl group which has a reactivehydrogen atom or (b) a cycloaliphatic or aromatic carboxylic acid mono-or dianhydride exhibit, when cured, a char yield of about 64-66 weightpercent when subjected to a temperature of about 950° C. in nitrogen.Unfortunately, these cured polymers exhibit a zero percent char yield at700° C. in air.

It has been discovered that when these polymers or prepolymers arereacted with an aqueous or alcoholic solution of a hydroxide, carbonateor bicarbonate of a metal of Groups I-A or II-A, the resultant curedproduct exhibits an improved char yield when subjected to a temperatureof 700° C. in air.

SUMMARY OF THE INVENTION

The present invention pertains to thermosettable polymers or prepolymersprepared by reacting

(A) the reaction product of

(1) a heterocyclic material having one or more rings and at least onenitrogen atom and at least two substituent groups which have at leastone reactive hydrogen atom attached to a carbon atom which is attachedto a heterocyclic ring;

(2) a cycloaliphatic or aromatic carboxylic acid mono- or dianhydride;and

(3) a material containing a polymerizable ethylenically unsaturatedgroup and at least one group selected from

(a) a heterocyclic material having one or more rings and at least onenitrogen atom and at least one substituent group which has at least onereactive hydrogen atom attached to a carbon atom which is attached to aheterocyclic ring or

(b) a cycloaliphatic or aromatic carboxylic acid mono- or dianhydridegroup with

(B) an aqueous or alcoholic solution of a hydroxide, carbonatebicarbonate, of a metal of groups I-A or II-A or combination thereof;

wherein the components of (A) are employed in a molar ratio of(1):(2):(3) of from about 1:0.25:0.25 to about 1:4:4, preferably fromabout 1:0.5:0.5 to about 1:1.5:1.5, respectively and components A and Bare present in quantities which is sufficient to react at least aportion, preferably from about 10 to about 100, most preferably fromabout 50 to about 100, percent of the anhydride and lactone groups incomponent (A) with an alkali metal or alkaline earth metal hydroxide,carbonate, bicarbonate or combination thereof with component (B).

Another aspect of the present invention pertains to the cured orthermoset product resulting from curing or thermosetting the abovepolymers or prepolymers by heat and pressure or by eitherhomopolymerization in the presence of at least one N,N'-bis-imide orcopolymerization with at least one N,N'-bis-imide.

DETAILED DESCRIPTION OF THE INVENTION

Suitable heterocyclic materials having one or more rings and at leastone nitrogen atom and at least two substituent groups which have atleast one reactive hydrogen atom attached to a carbon atom which isattached to a ring which can be employed herein include, for example,pyrazines, pyridines, pyrazoles, imidazoles, pyridazines, pyrimidines,purines, pteridines, triazines, quinolines and quinoxalines.Particularly suitable such substituent groups include methyl, --CH(R)₂or --CH₂ R groups wherein each R is independently a hydrocarbon groupcontaining from 1 to about 20, preferably from 1 to about 10 carbonatoms.

In order for the hydrogen atom of the substituent group which hydrogenatom is attached to a carbon atom attached to a heterocyclic ring to bereactive, the substituent group must be either ortho or para withrespect to a nitrogen atom. In the instance of substituted pyrazines,all of the substituent groups attached to a heterocyclic ring carbonatom are ortho with respect to a nitrogen atom.

Particularly suitable as the heterocyclic material which can be employedherein include the pyrazines such as, for example, 2,5-dimethylpyrazine,2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine,2,3,5,6-tetramethylpyrazine, 2,5-dimethyl-3,6-pyrazinediamine,2,3,5-trimethyl-6-nitropyrazine, 5-ethyl-2,6-dimethylpyrazine,2,5-dimethyl-3-propylpyrazine, 3-chloro-2,5,6-trimethylpyrazine,3-chloro-2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine,2,5-diethylpyrazine, 2-ethyl-3,5-dimethylpyrazine,2-ethyl-3,6-dimethylpyrazine, 5-methyl-2-propylpyrazine,3,5-dimethyl-2-propylpyrazine, 2-butyl-3,5-dimethylpyrazine,2-butyl-3,6-dimethylpyrazine, 2-butyl-5-ethylpyrazine,2,5-dimethyl-3,6-bis(2-methylpropyl)pyrazine,2,6-diethyl-3,5-dimethylpyrazine, 2,5-diethyl-3,6-dimethylpyrazine,2,5-dimethyl-3,6-bis(1-methylethyl)pyrazine, and2,3,5-trimethyl-6-(2-methylpropyl)pyrazine, mixtures thereof and thelike. Pyrazines having only one substituent group having a reactivehydrogen atom attached to a carbon atom which is attached to theheterocyclic ring, such as, for example, 2-methylpyrazine can be mixedor blended with pyrazine having two or more methyl substituents tocontrol the molecular weight of the prepolymer.

Particularly suitable pyridines which can be employed herein include,for example, 2,6-dimethylpyridine, 2,4-dimethylpyridine,2,3,4-trimethylpyridine, 2,3,6-trimethylpyridine,2,4,5-trimethylpyridine, 2-ethyl-3,6-dimethylpyridine,4-ethyl-2,6-dimethylpyridine, 2,6-diethylpyridine,2,3-dimethyl-6-(1-methylethyl)pyridine,3,6-dimethyl-2-(1-methylethyl)pyridine, 2-methyl-6-propylpyridine,2,5-dimethyl-6-propylpyridine, 3-ethyl-2,5,6-trimethylpyridine,2,3,4,5-tetramethylpyridine, 2,3,4,6-tetramethylpyridine,2,3,5,6-tetramethylpyridine, pentamethylpyridine,2,6-dimethyl-3-pyridinamine, 3-chloro-2,6-dimethylpyridine, mixturesthereof and the like. Pyridines having only one substituent group havinga reactive hydrogen atom attached to a carbon atom which is attached tothe ring, such as, for example, 2-methylpyridine, 4-methylpyridine,2-ethylpyridine, 2-propylpyridine and the like can be mixed or blendedwith pyridine having two or more alkyl groups to control the molecularweight of the prepolymer.

Other suitable aromatic nitrogen containing heterocycles which can beemployed herein include, pyrazoles, imidazoles, pyridazines,pyrimidines, purines, pteridines, triazines, quinolines and quinoxalineshaving two or more substituents having a reactive hydrogen atom attachedto a carbon atom which is attached to a heterocyclic ring. Suchsubstituent groups include methyl, --CH(R)₂ or --CH₂ R wherein R² is asabove defined.

Suitable pyrazoles include 3,5-dimethylpyrazole,1-ethyl-3,5-dimethylpyrazole, 3,4,5-trimethylpyrazole,3,5-diethylpyrazole, mixtures thereof and the like.

Suitable imidazoles which can be employed herein include1,2-dimethylimidazole, 2,5-dimethylimidazole, 2,4-dimethylimidazole,2,4,5-trimethylimidazole, 3-ethyl-4-methylimidazole, mixtures thereofand the like.

Suitable pyridazines include 3,5-dimethylpyridazine,4-chloro-3,5-dimethylpyridazine, 3,4,5-trimethylpyridazine,3,4,6-tripropylpyridazine, mixtures thereof and the like.

Suitable pyrimidines include 2,4-dimethylpyrimidine,4,6-dimethylpyrimidine, 2,6-dimethyl-4-pyridinamine,6-hydroxy-2,4-dimethylpyrimidine, 2,5-dihydroxy-4,6-dimethylpyrimidine,4,6-dimethylpyrimidin-2-yl mercapto acetic acid,2,4,6-trimethylpyrimidine, 2,4,6-tripropylpyrimidine, mixtures thereofand the like.

Suitable purines which can be employed herein include, for example,2,8-dimethylpurine, 2,8-dimethyl-6-purinamine, 2,6,8-trimethylpurine,mixtures thereof and the like.

Suitable pteridines include 6,7-dimethylpteridine,2,6-dimethylpteridine, 2,4,7-trimethylpteridine,2,4,6,7-tetramethylpteridine, mixtures thereof and the like.

Suitable triazines which can be employed herein include3,5-dimethyl-1,2,4-triazine, 3,6-dimethyl-1,2,4-triazine,3,5,6-trimethyl-1,2,4-triazine, 2,4-dimethyl-1,3,5-triazine,2,6-dimethyl-1,3,5-triazine, 2,4,6-trimethyl-1,3,5-triazine, mixturesthereof and the like.

Suitable quinolines include 2,4-dimethylquinoline,2,4,6-trimethylquinoline, 2,4,6,7-tetramethylquinoline, mixtures thereofand the like.

Suitable quinoxalines include 2,3-dimethylquinoxaline,2,3,7-trimethylquinoxaline, 2,3,6,8-tetramethylquinoxaline, mixturesthereof and the like.

Molecular weight control of the polymer can be obtained by the additionof an aromatic nitrogen containing heterocyclic material having onesubstituent group which has at least one reactive hydrogen atom attachedto a carbon atom which is attached to the heterocyclic ring as a chainterminator to an aromatic nitrogen containing heterocyclic materialhaving two or more substituent groups which have at least one reactivehydrogen atom attached to a carbon atom which is attached to theheterocyclic ring. As an example, pyrazoles, pyridines, imidazoles,pyridazines, pyrimidines, purines, pteridines, triazines, quinolines orquinoxalines having one substituent group which has at least onereactive hydrogen atom attached to a carbon atom which is attached tothe heterocyclic ring can be mixed with a cycloaliphatic or aromaticheterocycle containing one or more nitrogens and having two or moresubstituent groups which have at least one reactive hydrogen atomattached to a carbon atom which is attached to the heterocyclic ring.

Suitable dicarboxylic acid monoahydrides which can be employed hereininclude, for example, those represented by the formula ##STR1## whereinR is a divalent radical such as, for example, ##STR2## where R¹ isalkyl, or one of the following: ##STR3## wherein R² is alkyl, aryl oraralkyl, or such groups containing substituents such as, for example,halogen, nitro or amino and where R³ is alkylene, oxygen, sulfur,oxyalkylene, polyoxyalkylene, or one of the following: ##STR4## whereinR⁴ and R⁵ are alkyl, aryl or such groups containing substituents suchas, for example, halogen, nitro or amino.

The preferred monoanhydrides are those in which the carbon atoms of thepair of carbonyl groups are directly attached to ortho carbon atoms inthe R group to provide a 5-member ring such as, for example, ##STR5##

Suitable such monoanhydrides include, for example, phthalic anhydride,3-nitrophthalic anhydride, tetraphenylphthalic anhydride,tetrachlorophthalic anhydride, tetrabromophthalic anhydride,hexahydro-4-methylphthalic anhydride, pyrazine-2,3-dicarboxylicanhydride, pyridine-2,3-dicarboxylic anhydride,quinoxaline-2,3-dicarboxylic anhydride, 2-phenylglutaric anhydride,isatoic anhydride, N-methyl isatoic anhydride, 5-chloroisatoicanhydride, 5-nitroisatoic anhydride, diphenic anhydride, 1,8-naphthalicanhydride, 4-chloro-1,8-naphthalic anhydride, 3-nitro-1,8-naphthalicanhydride, 3,4-coronenedicarboxylic anhydride,trans-1,2-cyclohexaneanhydride, 3,3,-tetramethyleneglutaric anhydride,di-camphoric anhydride, mixtures thereof and the like.

Suitable tetracarboxylic acid dianhydrides which can be employed hereininclude, for example, those represented by the formula ##STR6## whereinR is a tetravalent aromatic radical such as, for example: ##STR7## whereR¹ is alkylene, oxygen, sulfur, oxyalkylene, polyoxyalkylene, or one ofthe following: ##STR8## wherein R² and R³ are alkyl, aryl or aralkyl, orsuch groups containing substituents such as, for example, halogen, nitroor amino.

Suitable such dianhydrides include, for example, pyromelliticdianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride,pyridine-2,3,5,6-tetracarboxylic dianhydride,pyrazine-2,3,5,6-tetracarboxylic dianhydride,naphthalene-2,3,6,7-tetracarboxylic dianhydride,naphthalene-1,4,5,8-tetracarboxylic dianhydride,naphthalene-1,2,4,5-tetracarboxylic dianhydride,2,6-dichloronaphthalene-1,4,5,8-tetracarboxylicdianhydride,2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylicdianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride,3,4,9,10-perylenetetracarboxylic dianhydride,thiophene-2,3,4,5-tetracarboxylic dianhydride,bis(3,4-dicarboxyphenyl)sulfone dianhydride,2,3,2',3'-benzophenonetetracarboxylic dianhydride,2,3,3',4'-benzophenonetetracarboxylic dianhydride,bis(2,3-dicarboxyphenyl)methane dianhydride,bis(3,4-dicarboxyphenyl)methane dianhydride,1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride,2,2-bis(2,3-dicarboxyphenyl)propane dianhydride,bis(3,4-dicarboxyphenyl)ether dianhydride,anthracene-2,3,6,7-tetracarboxylic dianhydride,fluorene-2,3,6,7-tetracarboxylic dianhydride,pyrene-1,2,7,8-tetracarboxylic dianhydride,quinoxaline-2,3,6,7-tetracarboxylic dianhydride,phenazine-2,3,7,8-tetracarboxylic dianhydride,1,1-bis(2,3-dicarboxy-5-oxyphenyl)ethane dianhydride, mixtures thereofand the like.

Tetracarboxylic acid dianhydrides can be mixed or blended withcycloaliphatic or aromatic monoanhydrides or mixtures of monoanhydrideswhich serve as chain terminators to control molecular weight of thepolymers.

Ethenyl (vinyl) termination agents or compounds containing at least onepolymerizable unsaturated group include (a) ethenyl substituted aromaticnitrogen heterocyclic compounds having one or more rings and at leastone substituent group which has at least one reactive hydrogen atomattached to a carbon atom which is attached to a heterocyclic ring and(b) a cycloaliphatic or aromatic carboxylic acid anhydride having atleast one polymerizable unsaturated group. Suitable ethenyl substitutedaromatic nitrogen heterocyclic compounds having at least one or moresubstituent group which has at least one reactive hydrogen atom attachedto a carbon atom which is attached to the heterocyclic ring include3-ethenyl-2-methylpyridine (2-methyl-3-vinylpyridine);5-ethenyl-2-methylpyridine (2-methyl-5-vinylpyridine);6-ethenyl-2-methylpyridine (2-methyl-6-vinylpyridine);2-(buta-1,3-dienyl)-6-methylpyridine; 6-methyl-2-(pent-1-enyl)pyridine;2-(but-1,3-dienyl)-4,6-dimethylpyridine;2-methyl-4(prop-1-enyl)pyridine;2-(6-(4-(1-methylethen-1-yl)cyclohex-1-enyl))-6-methylpyridine;2-(6-(4-(1-methylethen-1-yl)cyclohex-1-enyl))-4,6-dimethylpyridine;3,5-diethenyl-2-methylpyridine; 2,5-diethenyl-3,4-dimethylpyridine;3,5-diethenyl-2,4,6-trimethylpyridine;3-chloro-5-ethenyl-2,6-dimethylpyridine;5-ethenyl-6-ethyl-2-methylpyridine; 5-ethenyl-2-methyl-4-propylpyridine;3-ethenyl-2,6-diethylpyridine; 6-ethenyl-2,4-diethylpyridine;3-ethenyl-2-methylpyrazine (2-methyl-3-vinylpyrazine);5-ethenyl-2-methylpyrazine (2-methyl-5-vinylpyrazine);6-ethenyl-2-methylpyrazine (2-methyl-6-vinylpyrazine);5-ethenyl-2,6-dimethylpyrazine; 5-ethenyl-2,3,6-trimethylpyrazine;3,5-diethenyl-2,6-dimethylpyrazine; 5-ethenyl-2-ethyl-6-methylpyrazine;5-ethenyl-2,6-diethylpyrazine; 2-methyl-5-(1-methylethenyl)pyrazine;2-(2-ethylbut-1-enyl)-6-methylpyrazine;2-methyl-6-(2-methylprop-1-enyl)pyrazine;2-(but-1,3-dienyl)-6-methylpyrazine; 3,6-diethyl-2-(pen-1-enyl)pyrazine;2-(but-1,3-dienyl)-3,6-dimethylpyrazine;2-methyl-5-(prop-1-enyl)pyrazine;2-(6-(4-(1-methylethen-1-yl)cyclohex-1-enyl))-6-methylpyrazine;2-(6-(4-(1-methylethen-1-yl)-cyclohex-1-enyl))-5,6-dimethylpyrazine;2-(6-(4-(1-methylethen-1-yl)cyclohex-1-enyl))-3,5,6-trimethylpyrazine;5-ethenyl-3-methylpyridazine; 4-chloro-5-ethenyl-3-methylpyridazine;5-ethenyl-3,6-dimethylpyridazine; 4-ethenyl-2,6-dimethylpyrimidine;6-ethenyl-2-methyl-4-pyrimidinamine; 6-ethenyl-2,8-dimethylpurine;8-ethenyl-2,6-dimethylpurine; 6-ethenyl-8-ethyl-2-methylpurine;6-ethenyl-2-methyl-8-purinamine; 2-ethenyl-6,7-dimethylpteridine;6-ethenyl-2,4-dimethyl-1,3,5-triazine;5-ethenyl-3,6-dimethyl-1,2,4-triazine;5-ethenyl-3-methyl-6-propyl-1,2,4-triazine;7-ethenyl-2,4,8-trimethylquinoline;6,7-diethenyl-2,4,8-trimethylquinoline;6-ethenyl-2,3,8-trimethylquinoxaline; 4-ethenyl-2,5-dimethylimidazole;4-ethenyl-3,5-dimethylpyrazole and their mixtures.

Suitable cycloaliphatic or aromatic carboxylic acid monoanhydrideshaving at least one polymerizable unsaturated group are represented bythe formula: ##STR9## in which R is a hydrogen, halogen or a 1 to 4carbon alkyl group and X is either --CH₂ --, --CH₂ CH₂ --, --O--,--NH--, --CCl₂ --, or --S--. Preferred cyclic or aromatic carboxylicacid anhydrides having at least one polymerizable unsaturated groupinclude 3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride(cis-5-norbornene-endo-2,3-dicarboxylic anhydride),endo-bicyclo[2.2.2.]octa-5-ene-2,3-dicarboxylic anhydride,3,6-endoxo-1,2,3,6-tetrahydrophthalic anhydride(7-oxa-bicyclo[2.2.1.]hept-5-ene-2,3-dicarboxylic anhydride),1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic anhydride, mixturesthereof and the like. Other cyclic or aromatic carboxylic anhydridesinclude cis-1,2,3,6-tetrahydrophthalic anhydride(cis-4-cyclohexane-1,2-dicarboxylic anhydride), citraconic anhydride,2,3-dimethylmaleic anhydride, dichloromaleic anhydride, combinationsthereof and the like.

Suitable bases that can be reacted with the anhydride and lactone groupsof the ethenyl terminated prepolymer or polymer includes the hydroxides,carbonates and bicarbonates of the alkali metal and alkaline earthmetals. Suitable alkali metal and alkaline earth metals include sodium,potassium, lithium, calcium, barium, magnesium and cesium. Particularlysuitable metals are sodium, potassium, calcium and magnesium.

Suitable alkali metal or alkaline earth metal hydroxides, carbonates orbicarbonates include, for example, sodium hydroxide, potassiumhydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide,magnesium hydroxide, sodium carbonate, potassium carbonate, lithiumcarbonate, barium carbonate, calcium carbonate, magnesium carbonate,sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, bariumbicarbonate, calcium bicarbonate, magnesium bicarbonate, mixturesthereof and the like.

The alkali metal or alkaline earth metal carboxylic acid salt of theethenyl terminated prepolymers or polymers can be prepared by reactingthe alkyl substituted aromatic nitrogen heterocyclic material,cycloaliphatic or aromatic carboxylic mono- or dianhydride, vinyltermination agent and aqueous or methanolic solution of alkali metal oralkaline earth metal hydroxide, carbonate or bicarbonate in a two orthree step process. The two step process comprises (1) condensing thealkyl substituted aromatic nitrogen heterocyclic material,cycloaliphatic or aromatic carboxylic mono- or dianhydride with thevinyl termination agent to form ethenyl terminated prepolymer or polymerand then (2) reacting the ethenyl terminated prepolymer or polymer withan aqueous or methanolic solution of alkali metal or alkaline earthmetal hydroxide, carbonate or bicarbonate. The three step processcomprises (1) condensing the alkyl substituted aromatic nitrogenheterocyclic material with a cycloaliphatic or aromatic carboxylic mono-or dianhydride to form a prepolymer, (2) condensing the vinyltermination agent with the prepolymer to form ethenyl terminatedprepolymer or polymer and then (3) reacting the ethenyl terminatedprepolymer or polymer with an aqueous or alcoholic solution of alkalimetal or alkaline earth metal hydroxide, carbonate or bicarbonate. Thecondensation of alkyl substituted aromatic nitrogen heterocyclicmaterials, cycloaliphatic or aromatic carboxylic mono- or dianhydrideand vinyl termination agent can be carried out neat or in the presenceof a solvent. A solvent is preferred. Dehydration conditions aresuitably provided by a dehydrating agent and/or a catalyst to activatethe alkyl groups. In the condensation steps without a vinyl terminationagent, condensation is carried out at a temperature of from about 50° toabout 220° C., preferably from 120° to 180° C. for about 10 minutes to128 hours (600 s to 460,800 s), especially 30 minutes to 64 hours (1800s to 230,400 s). In the condensation steps with a vinyl terminationagent, condensation is carried out at a temperature of from 50° to about140° C., preferably from 80° to 120° C. for about 1 to 64 hours (3600 sto 230,400 s), preferably from 6 to 24 hours (21,600 s to 86,400 s). Thereaction of an aqueous or methanolic solution of alkali metal oralkaline earth metal hydroxide, carbonate or bicarbonate with theethenyl terminated prepolymer or polymer can be carried out at atemperature of from 0° to 220° C., preferably from 25° to about 140° C.for about 10 minutes to 24 hours (600 s to 86,400 s), preferably from 30minutes to 6 hours (1800 s to 21,600 s).

Suitable solvents include ketones, ethers, amides, acids, aromaticheterocycles containing no substituent groups which have at least onereactive hydrogen atom attached to a carbon atom which is attached tothe ring, chlorinated solvents and the like. Particularly suitablesolvents include, tetrahydrofuran, pyridine, glacial acetic acid,dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide,N,N-dimethylmethoxyacetamide, hexamethylphosphotriamide,N-methyl-pyrrolidinone, mixtures thereof and the like.

Suitable catalysts include, for example, acids, Lewis acids, bases orsalts. Particularly suitable acids include, for example, sulfuric,hydrochloric, acetic or p-toluene-sulfonic acid. Particularly suitableLewis acids include boron trifluoride. Particularly suitable basesinclude, for example, hydroxides of alkali or alkaline earth metals orof quaternary ammonium. Particularly suitable salts include, forexample, zinc chloride or aluminum chloride. The use of such catalystsis not indispensable but it reduces the time required for the reaction.The amount is e.g. of from about 0.1 to about 10 mole% wth respect tothe cycloaliphatic or aromatic carboxylic acid mono or dianhydride. Ifdesirable, larger or lesser quantities can be employed.

The reaction can also be accelerated by certain substances such asmethyl iodide, methyl sulfate, benzyl chloride etc., capable of formingwith the pyrazinic base quaternary ammonium derivatives, such substancesbeing usable in catalytic amounts or higher proportions.

Dehydrating agents such as acetic anhydride, trifluoroacetic anhydride,propionic anhydride and the like can promote the reactions and itsaction can be sufficient to render superfluous the incorporation of acatalyst. The amount of anhydride used ranges from 1 to 10 moles permole of vinyl termination agent, preferably 1.1 to 5. The preferreddehydrating medium is a mixture of glacial acetic acid and aceticanhydride. The acetic acid and acetic anhydride can be removed bydistillation, solvent extraction, solvent fractionation orneutralization with a base. Examples of several solvent fractionationmethods are described in U.S. Pat. Nos. 4,362,860 and 4,471,107 whichare incorporated herein by reference.

The reaction is usually conducted either under reduced pressure or in aninert atmosphere such as, for example, nitrogen, helium, neon, xenon,argon, mixtures thereof and the like.

Volatile emission during cure can be limited by subjecting thethermosettable prepolymers or resins of the present invention tosublimation, distillation or solvent extraction to remove reactants,catalyst and solvents. Suitable solvents for extraction include, forexample, alcohols, acetonitrile, ethers, water, hydrocarbons,chlorinated solvents and the like. Particularly suitable solventsinclude acetonitrile, methanol, ethanol, water, mixtures thereof and thelike.

The thermosettable prepolymers or resins of the present invention can becured as is with the application of heat and pressure, or they can bedissolved in a suitable solvent or mixture of solvents and employed tosaturate various reinforcing materials so as to prepare compositestherefrom through the application of heat and pressure.

Suitable solvents which can be employed to saturate the variousreinforcing materials include, for example, ketones, acetates, alcohols,ethers, hydrocarbons and the like. Particularly suitable solventsinclude, for example, acetone, methylethylketone, ethyl acetate,methylene chloride, trichloroethylene, tetrahydrofuran, chlorobenzene,ethanol, n-propanol, N-methyl-pyrrolidinone, dimethylformamide,dimethylacetamide, nitrobenzene, mixtures thereof and the like.

Suitable reinforcing materials include, for example, glass fibers,polyamide fiber, carbon or graphite fibers and the like in any form suchas, for example, matt, woven or fibrous form. Any synthetic or naturalfiber material can be employed as the reinforcing material.

The thermosettable prepolymers can be used according to variousconventional techniques applicable to thermosetting resins. Powderedprepolymers are especially adapted for shaping by pressure-molding, butthey can also be dissolved in a solvent or be employed in molten form.They can be used in the preparation of laminates or composites, films,coatings, encapsulants and the like.

The prepolymer is advantageously set by a thermal treatment at atemperature of from about 100° to about 300° C. When pressure molding,pressures up to about 100,000 psig (689 MPa) can be employed. Saidpolymer has a good thermal stability.

The alkali metal or alkaline metal carboxylic acid salt of the vinylterminated prepolymer or polymers can either be homopolymerized(blended) in the presence of a N,N'-bis-imide or copolymerized with aN,N'-bis-imide of the formula: ##STR10## in which X represents adivalent radical containing a carbon-carbon double bond and A is adivalent radical having at least 2 carbon atoms. PreferredN,N'-bis-imides which may be employed, are1,1'-(1,2-ethanediyl)bis-1H-pyrrole-2,5-dione;1,1'-(1,6-hexanediyl)bis-1H-pyrrole-2,5-dione;1,1'-(1,4-phenylene)bis-1H-pyrrole-2,5-dione;1,1'-(1,3-phenylene)bis-1H-pyrrole-2,5-dione;1,1'-(methylenedi-4,1-phenylene)bis-1H-pyrrole-2,5-dione,[1,1'-(methylenedi-4,1-phenylene)bismaleimide];1,1'-(oxydi-4,1-phenylene)bis-1H-pyrrole-2,5-dione;1,1'-(sulfonyldi-4,1-phenylene)bis-1H-pyrrole-2,5-dione;1,1'-(methylenedi-4,1-cyclohexanediyl)bis-1H-pyrrole-2,5-dione;1,1'-[1,4-phenylenebis(methylene)]bis-1H-pyrrole-2,5-dione;1,1'-[(1,1-dimethyl-3-methylene-1,3-propanediyl)di-4,1-phenylene]bis-1H-pyrrole-2,5-dione;1,1'-[(1,3,3-trimethyl-1-propene-1,3-diyl)di-4,1-phenylene]bis-1H-pyrrole-2,5-dione;and Technochemie's H-795 and M-751 resins. Technochemie's H-795 resin isrepresented by the formula: ##STR11## where R is an aromatic ring andX-R₁ -X is a Michael addition coupling group. Technochemie's M-751 resinis a "eutectic" mixture of ##STR12## many of these and other suitableN,N'-bis-imides which can be employed herein are disclosed in U.S. Pat.No. 3,562,223 which is incorporated herein by reference.

The following examples are illustrative of the invention, but are not tobe construed as to limiting the scope thereof in any manner.

EXAMPLE 1

2,3,5,6-Tetramethylpyrazine (91.6 g, 0.67 mole), pyrometilliticdianhydride (218 g, 1 mole) and acetic acid (121 g, 2.01 moles) werestirred in a one liter reaction vessel equipped with a mechanicalstirrer, thermometer, nitrogen gas inlet and condenser. Afterdeoxygenation by purging with nitrogen, acetic anhydride (204 g, 2moles) was added to the reaction vessel. The reactants were heated to atemperature between 104° C. and 133° C. for a period of 38 minutes (2280s). The reaction mixture was cooled to 90° C. and2-methyl-5-vinylpyridine (80 g, 0.67 mole) was added to the reactionvessel. The reactants were heated to a temperature between 118° C. and124° C. for 11 hours and 20 minutes (40,800 s). On cooling to roomtemperature (22° C.), the reaction product was a black solid.

The resultant solid prepolymer was ground to a powder and neutralizedwith 10 wt.% sodium hydroxide solution while stirring between 60° C. and80° C. for 6 hours (21,600 s). This solution was vacuum filtered. Theblack shiny filtrant (10-20 g) did not melt at 350° C.; therefore, itwas discarded. A black solid product was recovered after rotaryevaporation of the black colored filtrate. A sandy brown coloredprepolymer was obtained after the black solid was methanol washed, driedin a vacuum oven between 80° C. and 90° C. and 30 inches (1 mm) Hgvacuum overnight and sieved with a U.S.A. Standard Testing Sieve No. 40.The sandy brown colored prepolymer melted between 240° C. and 260° C.

A proton ('H) nuclear magnetic resonance (NMR) spectrum verified thatthe structure of the prepolymer contained methyl, terminal unsaturated(--CH═CH₂), internal unsaturated (--CH═C) and aromatic protons whichwere observed by NMR absorption bands at 0.6, 5.4, between 6.0 and 6.1and 7.6 to 8 parts per million, respectively.

The infrared spectra of the prepolymer showed a strong asymmetricalstretching band near 1580 cm⁻¹ and a symmetrical stretching band at 1400cm⁻¹ from carboxylate ion. The spectra did not support free carboxylicacid which indicates the prepolymer was a carboxylic acid salt.

Flame emission spectroscopy showed the carboxylic acid salt of theethenyl terminated prepolymer after treating with sulfuric acid andburning at 500° C. in air contained 15 wt.% sodium.

The sandy brown colored prepolymer was compression molded between 280°C. and 259° C. and 6800 psi (46,885 kPa) for 2 hours (7200 s) with aCarver Laboratory press, employing a silicone mold release agent. Thebrown cured polymer was post cured for 15 hours (54,000 s) at 255° C.Thermogravimetric analysis of the cured polymer in a nitrogen atmosphereresulted in a 5% weight loss at 383° C. and an 82% weight loss at 950°C. In air, the polymer lost 5% by weight at 370° C. and 33% by weight at700° C.

EXAMPLE 2

The vinyl terminated prepolymer (13 g) prepared in Example 1 was mixedwith oven dried and sieved 1,1'-(methylenedi-4,1-phenylene)bismaleimide(13 g, 0.036 mole) to yield a sandy brown colored powder. This mixtureof prepolymers was compression molded between 260° C. and 303° C. at6550 psi (45,161 kPa) for 2 hours (7200 s) with a Carver Laboratorypress, employing a silicone mold release agent. The resulting dark browncured polymer was post cured for 15 hours (54,000 s) at 255° C.Thermogravimetric analysis of the cured polymer in a nitrogen atmosphereresulted in a 5% weight loss at 310° C. and a 77.5% weight loss at 950°C. In air, the product lost 5% by weight at 353° C. and 47.5% at 700° C.Dynamic mechanical analyses was performed between -160° C. to 400° C. inthe torsional rectangular mode with an oscillatory frequency of 1 hertzand 0.05% strain. The sodium containing polymer exhibited no glasstransition temperature up to 355° C., no apparent gamma transition(T.sub.γ) and storage modulus (G') of 9.198×10⁹ dynes/cm² at 25° C.

COMPARATIVE EXPERIMENT A

Oven dried and sieved 1,1'-(methylenedi-4,1-phenylene)bismaleimide (20g, 0.056 mole) was compression molded between 255° C. and 300° C. at7200 psi (49,643 kPa) for 2 hours (7200 s) with a Carver Laboratorypress, employing a silicone mold release agent. The yellowish browntranslucent polymer was post cured for 15 hours (54,000 s) at 255° C.Thermogravimetric analysis of the cured polymer in a nitrogen atmosphereshowed a 5% weight loss at 490° C. and a 51.5% weight loss at 950° C. Inair, the polymer lost 5% by weight at 428° C. and 100% by weight at 700°C. The cured sodium carboxylic acid salt of the ethenyl terminatedprepolymer either homopolymerized in the presence of1,1'-(methylenedi-4,1-phenylene)bismaleimide or copolymerized with1,1'-(methylenedi-4,1-phenylene)bismaleimide described in Example 2 ismuch more thermally stable in air at 700° C. than1,1'-(methylenedi-4,1-phenylene)bismaleimide cured by itself.

I claim:
 1. A process for preparing an alkali or alkaline earth metalcarboxylic acid salt of an ethenyl (vinyl) terminated prepolymer orpolymer which comprises:(1) reacting in a mixture of a solvent anddehydration agent(a) at least one heterocyclic material having one ormore rings therein, at least one nitrogen atom in a ring and at leasttwo substituent groups which have at least one reactive hydrogen atomattached to a carbon atom which is attached to a heterocyclic ring with(b) at least one cycloaliphatic or aromatic carboxylic acid cyclic mono-or dianhydride at a temperature in the range of about 50° C. to about250° C. for about 10 minutes to 128 hours; (2) adding a materialcontaining a polymerizable ethylenically unsaturated group to thereaction mixture of step (1) and heating at a temperature in the rangeof about 50° C. to about 140° C. for about 1 to about 64 hours; (3)adding an aqueous or alcoholic solution of a hydroxide, carbonate orbicarbonate of an alkali metal or alkaline earth metal to the reactionmixture of step (2) at a temperature in the range of about 0° to about220° C. for about 10 minutes to 24 hours, and (4) recovering the alkalior alkaline earth metal carboxylic acid salt of the ethenyl terminatedprepolymer or polymer.
 2. A process of claim 1 wherein said solvent isglacial acetic acid and said dehydration agent is acetic anhydride.
 3. Aprocess of claim 2 wherein step (4) is accomplished by distillation,solvent extraction, solvent fractionation or neutralization with a base.4. A process of claim 3 wherein recovery step (4) is accomplished bysolvent extraction using acetonitrile, methanol or water.
 5. A processof claim 4 wherein step (1) is conducted at a temperature in the rangeof from about 130° C. to about 145° C., step (2) is conducted at atemperature in the range of from about 105° C. to about 125° C., andstep (3) is conducted at a temperature in the range of from about 25° C.to about 140° C.
 6. A process of claim 5 wherein component (3) is anaqueous solution of sodium hydroxide.